The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Automatic transmissions provide a plurality of forward and reverse speed or gear ratios by selectively actuating one or more brakes or clutches. One type of brake or clutch useful in automatic transmissions is known as a one-way clutch. A one-way clutch includes a “locked” mode in one rotational direction and a “freewheel” mode in the opposite rotational direction. Some existing transmissions use a passive one-way clutch deployed in parallel with a plate clutch that is generally actuated in a first gear ratio and not actuated in a second gear ratio. Some transmission designs, however, are not compatible with these passive one-way clutch configurations because the members must be able to rotate with respect to each other in the direction not allowed by the passive one-way clutch while in certain gear ratios. One solution is to use a plate clutch instead of the one-way clutch configuration. The plate clutch, however, does not allow “freewheeling,” or rotation in the direction opposite the direction of torque transfer, and takes up more space and causes more rotational energy loss than a one-way clutch for a predetermined clutch torque limit. The freewheeling capability is useful for avoiding unintended engine braking in the first gear ratio and for simplifying shifts into and out of the first gear ratio.
Thus, there is a need for a new and improved clutch assembly that provides beneficial operating modes while minimizing increases in mass, cost, and inefficiencies.